What cause damage to my 350 Chev?

[tgzzzz]

Any theories on what caused this damage to my 350 Chev in motorhome? 2 plug gaps were squeezed shut. Truck still started and ran OK although didn't produce much power.

[03chevy]

did you have any head work done? or know of any head work been done? if so then they shaved the head to far and the piston hit the plug

[436'd skylark]

Was the motor rebuilt with hyper pistons?



Otherwise something got through the motor.

[75K30]

Foriegn object in the engine.
Thise pistons are hammered, and much of the damage looks to be from something inside of the cylinder.
How does the combustion chamber look?
I might have first assumed that perhaps the timing chain was bad, and the piston made contact with the plugs, but the location where the pistons are broken do not support this theory.
Smaller pits are not visible, so detonation may not have been an issue, and the sharp cuts in the piston would indicate a foreign object.
Tough to imagine anything getting past the air filter, but perhaps something from the carb failed. Have you inspected the carb real well?
Maybe something from here fell into the intake, and caused you trouble????
Just a guess.

[mrjohnwayne]

I would have to Agree with 75. Looks like something foreign was bouncing around in there.

[tjzz4]

Sure there was.... Piston pieces. If I am not mistaken that is the top ring you are looking at on the top edge. Either it is leaned out or you have had some seroius detonation problems.

[mrjohnwayne]

Originally Posted by tjzz4

Sure there was.... Piston pieces. If I am not mistaken that is the top ring you are looking at on the top edge. Either it is leaned out or you have had some seroius detonation problems.

Good eye!

Looking back at it all 3 pistons in the picture are the same. missing chunks out of the top part of the piston.

[tgzzzz]

Originally Posted by tjzz4

Sure there was.... Piston pieces. If I am not mistaken that is the top ring you are looking at on the top edge. Either it is leaned out or you have had some seroius detonation problems.

Good eye indeed. That is the top ring visible. This was a 10K Goodwrench remanned engine.

So what happened? I was driving along and felt a loss of power. Managed another 100 miles along I-95 with less and less power. 3 pistons on the pass side are damaged and I don't have the driver's side head off yet. I've been drinking and crying in my beer so far but engine will be out next week.

When this happened, I noticed way too much oil vapor being fed into carb (oil running out of air cleaner) and PVC valve hose (blown?) out of valve cover, and loose air pump belt.

My theory is air pump quit sucking air out of oil pan, pressure built up to force oil vapor out of crankcase, blowing PVC valve out of place, then ...... what?????

How can I avoid this in the future?

[Jessie]

It appears that the groove on the piston let the ring come out and a piece broke off and got on top. Is the block cracked now? If the engine is rebuilt maybe wrong size pistons used for the bore. Or could be a piece of the piston on the side is gone. About the oil vapor I'd say that was compression going by the piston and back thru the oil pan.

[Sneakysportsman]

Correct me if I am wrong but those pistons look like they weren't clearenced right to the Cyl walls resulting in a Squeeze at the top of the stroke. Or the pistons were getting out of line during the down stroke- over-bore with under sized pistons. rip that head gasket off and post another pic so we can see piston at the top of the stroke.